The invention relates to vibration damping apparatus in general, and more particularly to improvements in apparatus for damping torsional vibrations, for example, between the engine and the wheels of a motor vehicle, especially between the crankshaft of the engine and the input element of the variable-speed transmission in a motor vehicle.
It is known to provide a torsional vibration damping apparatus with a rotary input member (e.g., a flywheel which is affixed to the crankshaft of the engine in a motor vehicle), a rotary output member which is coaxial with the input member and can include a second flywheel which cooperates with a pressure plate of a friction clutch to transmit torque to the input element of the transmission when the clutch is engaged, and at least one damper operating between the two flywheels and including energy storing elements acting in the circumferential direction of an annular chamber which is defined by one of the flywheels, e.g., by the first flywheel. The other flywheel then comprises sections which extend into the chamber and engage the ends of the energy storing elements. The one flywheel is provided with means for supporting the energy storing elements so that each energy storing element reacts against the respective supporting means and bears against the respective section when the first flywheel turns relative to the second flywheel, and that each energy storing element reacts against the respective section and bears against the respective supporting means when the second flywheel turns relative to the first flywheel. Reference may be had, for example, to published German patent application No. 37 21 711. The supporting means which are disclosed in this German patent application can constitute discrete stops which are affixed to walls forming part of the first flywheel and defining the annular chamber, or the supporting means can constitute stops in the form of integral projections on such walls. Reference may also be had to commonly owned U.S. Pats. Nos. 4,816,006 and 4,946,420 which disclose flywheels one of which has a lubricant-containing annular chamber for coil springs and the radially outer portions of the coil springs bear against inserts which are installed in the radially outermost portion of the chamber.